This invention relates in general to an information storage device and, more particularly, to an information storage device in which a cartridge containing a storage media can be removably inserted into a cradle.
Over the past twenty years, computer technology has evolved very rapidly. One aspect of this evolution has been a progressively growing demand for increased storage capacity in memory devices, especially where the information storage medium is disposed in some form of removable cartridge. In this regard, just a little over a decade ago, the typical personal computer had a floppy disk drive which accepted floppy disk cartridges that contained a 5.25-inch disk with a storage capacity up to about 720 KB per cartridge. Not long thereafter, these devices gave way to a new generation of floppy disk drives, which accepted smaller floppy disk cartridges each containing a 3.5-inch disk having a higher storage capacity of about 1.44 MB per cartridge.
Subsequently, as the evolution continued, a further significant increase in storage capacity was realized in the industry by the introduction of a storage system having removable cartridges containing floppy-type disks with storage capacities on the order of 100 MB to 250 MB. Systems of this type are commercially available under the tradename ZIP from Iomega Corporation of Roy, Utah, which is the assignee of the present application. Thereafter, another significant increase in storage capacity was realized by the introduction of a system having removable cartridges with storage capacities on the order of 1 GB to 2 GB. Systems of this type are also available from Iomega Corporation, under the tradename JAZ. These two products have each enjoyed immense commercial success. Nevertheless, the demand for still greater storage capacities in removable cartridges continues to progressively increase, such that there is a current demand for cartridges capable of storing 5 GB to 20 GB, or even more.
The types of removable cartridges discussed above each contain a rotatably supported storage medium within an unsealed housing. The read/write heads, with associated circuitry and support structure, are in the drive rather than in the cartridge. Significantly higher storage capacities exist in hard disk technology of the type used in non-removable hard disk drives, where the disk and head are both disposed within a sealed housing. However, there are problems involved in attempting to carry use of this technology over to removable cartridges. This is due in part to the fact that a high-capacity hard disk is highly sensitivity to environmental factors such as dust and static electricity. Consequently, in order to achieve high storage densities, the sealed housing is needed for the hard disk itself, as well for some associated components (such as the read/write heads) that must be within the sealed housing and thus within the cartridge.
A further consideration is that a drive electronics circuit is typically mounted to the outside of the sealed housing of a hard disk drive, and contains a relatively complex and sophisticated circuit that controls the hard disk drive structure within the sealed housing. Where a hard disk drive mechanism is incorporated into a removable cartridge, it is desirable that the drive electronics circuit be implemented in the cradle which receives the cartridge, in order to avoid adding the cost of this circuit to the price of every cartridge. Further, it is desirable that the cradle use a pre-existing and commercially available drive electronics circuit, rather than a custom circuit designed specifically for the cradle. However, pre-existing drive electronics circuits have designs which reflect the expectation that they will be physically and electrically coupled at all times to the hard disk drive mechanism. They do not have the capability to deal with various considerations which arise as a result of the fact that the cartridge with the hard disk drive mechanism is removable from the cradle.
Still another consideration is that different users will wish to couple the cradle to various different types of standard computer interfaces. Various bridge circuits are commercially available to provide an interface between the communication protocol used to interact with the drive electronics circuit of a standard hard disk drive, and a respective one of several different communication protocols used to interface peripheral devices to computers. It would be desirable to be able to provide a cradle which can accept any one of these bridge circuits with little or no change in other circuitry of the cradle. Further, it would be desirable to use hardware of the bridge circuit to handle some or all of the considerations relating to removability of the cartridge.
Unfortunately, the hardware of these bridge circuits tends to vary significantly from one type of bridge circuit to another type of bridge circuit. Although some have spare outputs that might possibly be useful in handling at least some of the considerations relating to removability, others have no such spare outputs. In any event, the hardware differences among these various types of bridge circuits are such that there is no straightforward way to define a standardized approach to use of hardware of these bridge circuits to handle removability considerations.
Still another consideration is that some existing drive electronics circuits occasionally carry out commands that take a relatively long period of time, such as formatting of a hard disk, and tend to tie up an associated bus throughout the duration of the command. Considerations relating to removability may present issues that should be dealt with during the long command, but which cannot be handled using the bus if it is tied up by the drive electronics circuit.
According to one form of the present invention, a method and apparatus are provided and involve a cartridge having a data storage section and a first coupling portion operatively coupled to the data storage section, and a receiving section having a cartridge receiving portion which can removably receive the cartridge. The receiving section includes: a first control circuit; a bus controlled by the first control circuit; a second control circuit; a second coupling portion operatively coupled to the second control circuit and positioned so that the second control circuit can communicate with the data storage section through the first and second coupling portions when the cartridge is removably received in the cartridge receiving portion; a bus switch operatively coupled between the bus and the second control circuit, the switch having first and second operational modes in which the switch respectively effects and inhibits an operative coupling of the second control circuit to the bus; and an auxiliary circuit operatively coupled to the bus and to the bus switch, the auxiliary circuit being responsive to switch control information received from the first control circuit through the bus for causing the switch to operate in a selected one of the first and second operational modes specified by the switch control information.